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Prometheus function reference

.prom Prometheus Exporter interface

Create metrics
addmetric Create a metric instance
newmetric Define a new metric class

Update metric values
updval Update a metric value

Initialize library
init Initialize the library

Once the relevant event handlers have been defined to update the metric values, initialize the library with a call to .prom.init.

👉 Modify the behavior of event handlers that control the logic of metric updates

.prom.addmetric

Create a metric instance

.prom.addmetric[metric;labelvals;params;startval]

Where

  • metric is a symbol denoting the metric class being used
  • labelvals are the values of labels used to differentiate metric characteristics as a symbol/list of symbols
  • params are the parameters relevant to the metric type as a list of floats
  • startval is a float denoting the starting value of the metric

returns identifier/s for the metric, to be used in future updates.

// Tables
q)numtab1:.prom.addmetric[`number_tables;`amer;();0f]
q)numtab2:.prom.addmetric[`number_tables;`emea;();0f]
q)numtab3:.prom.addmetric[`number_tables;`apac;();0f]

// Updates
q)updsz:.prom.addmetric[`size_updates;();0.25 0.5 0.75;`float$()]

Once created, a metric will automatically be included in each HTTP response to a request from Prometheus.

.prom.init

Initialize metric monitoring

.prom.init[]
q).prom.init[]

Updating .z.* handlers after the call to .prom.init will overwrite the Prometheus logic.

Tip: Load all process logic before loading the Prometheus library.

.prom.newmetric

Define a metric class

.prom.newmetric[metric;metrictype;labelnames;helptxt]

Where

  • metric is a symbol denoting the name of the metric class
  • metrictype is a symbol outlining the type of metric
  • labelnames is a symbol or list of symbols denoting the names of labels used to differentiate metric characteristics
  • helptxt is a string providing the HELP text which is provided with the metric values
// Tables
q).prom.newmetric[`number_tables;`gauge;`region;"number of tables"]

// Updates
q).prom.newmetric[`size_updates;`summary;();"size of updates"]

.prom.updval

Update a metric value

.prom.updval[name;func;arg]

Where

  • name is a symbol denoting the metric instance being updated
  • func is a function/operator used to update the value
  • arg is the second argument provided to func (the first argument being the value itself)

When updating a single-value metric (counter or gauge), the value will typically be incremented, decremented or assigned to. This value will be reported directly to Prometheus.

When updating a sample metric (histogram or summary), a list of numeric values will typically be appended to. This list will be aggregated to provide statistics to Prometheus according to the metric type and parameters provided.

// Tables
q).prom.updval[`numtab1;:;count tables[]] // set
q).prom.updval[`numtab2;+;1]              // increment
q).prom.updval[`numtab3;-;1]              // decrement

// Updates
q).prom.updval[`updsz;,;10 15 20f]        // append